Effects of Varying Modes of Perfusion on Ovum Maturation and Ovulation in the Perfused Rabbit Ovary

Using a perfused rabbit ovary, we studied the effect of luteinizing hormone (LH) secretion on the ovulation time and the maturity of ova with 2 modes of perfusion. One mode consisted of a constant level of human chorionic gonadotropin (hCG) in the medium (the constant mode of perfusion), and the other mode mimicked the profile of LH surge in the rabbit (the surge mode of perfusion). The mean numbers of ova ovulated in the 2 modes were almost equal. The mean ovulation time in the constant mode was shorter than that in the surge mode. In the constant mode, the percentage of ova in germinal vesicle stage was larger, and in metaphase II was smaller, than those in the surge mode, while the difference in metaphase I was insignificant. The results indicate that the maturities of the ova in the surge mode were more advanced than those in the constant mode. A reason for the occurrence of the difference might be the early occurrence of ovulation in the constant mode due to excessive action on the follicular wall by various proteolytic enzymes, which are activated by the higher concentration of hCG, when compared with that of the surge mode, in the latter half of the perfusion.